"She suggested hauling bikes when we camp for exercise and to see some scenery. I don't have a rear hitch receiver and would be limited to one of the racks that uses the bumper mounted spare, a bumper mounted rack or a rack that hangs off my rear ladder."
I can't hardly believe you, of all people, would consider any kind of rack that wasn't attached to a receiver that was welded/bolted to the frame
IMHO it's the only way to properly carry bikes. A good quality Thule, Yakima, ettc. receiver mounted rack
